Patricia N. Coan DVM, PhD Copyright (c) 2012 All rights reserved. http://works.bepress.com/patricia_coan Recent documents in Patricia N. Coan DVM, PhD en-us Mon, 26 Nov 2012 05:16:23 PST 3600 Unique Long Terminal Repeat and Surface Glycoprotein Gene Sequences of Feline Leukemia Virus as Determinants of Disease Outcome http://works.bepress.com/patricia_coan/8 http://works.bepress.com/patricia_coan/8 Fri, 05 Aug 2011 09:31:30 PDT The outcome of feline leukemia virus (FeLV) infection in nature is variable, including malignant, proliferative, and degenerative disorders. The determinants of disease outcome are not well understood but are thought to include viral, host, and environmental factors. In particular, genetic variations in the FeLV long terminal repeat (LTR) and SU gene have been linked to disease outcome. FeLV-945 was previously identified as a natural isolate predominant in non-T-cell neoplastic and nonneoplastic diseases in a geographic cohort. The FeLV-945 LTR was shown to contain unique repeat elements, including a 21-bp triplication downstream of the enhancer. The FeLV-945 SU gene was shown to encode mutational changes in functional domains of the protein. The present study details the outcomes of infection with recombinant FeLVs in which the LTR and envelope (env) gene of FeLV-945, or the LTR only, was substituted for homologous sequences in a horizontally transmissible prototype isolate, FeLV-A/61E. The results showed that the FeLV-945 LTR determined the kinetics of disease. Substitution of the FeLV-945 LTR into FeLV-A/61E resulted in a significantly more rapid disease onset but did not alter the tumorigenic spectrum. In contrast, substitution of both the FeLV-945 LTR and env gene changed the disease outcome entirely. Further, the impact of FeLV-945 env on the disease outcome was dependent on the route of inoculation. Since the TM genes of FeLV-945 and FeLV-A/61E are nearly identical but the SU genes differ significantly, FeLV-945 SU is implicated in the outcome. These findings identify the FeLV-945 LTR and SU gene as determinants of disease.

]]> Chandtip Chandhasin et al. Subtle Mutational Changes in the SU Protein of a Natural Feline Leukemia Virus Subgroup A Isolate Alter Disease Spectrum http://works.bepress.com/patricia_coan/7 http://works.bepress.com/patricia_coan/7 Fri, 05 Aug 2011 09:31:28 PDT FeLV-945 is a representative isolate of the natural feline leukemia virus (FeLV) variant predominant in non-T-cell malignant, proliferative, and degenerative diseases in a geographic cohort. The FeLV-945 surface glycoprotein (SU) is closely related to natural horizontally transmissible FeLV subgroup A (FeLV-A) but was found to differ from a prototype to a larger extent than the members of FeLV-A differ among themselves. The sequence differences included point mutations restricted largely to the functional domains of SU, i.e., VRA, VRB, and PRR. Despite the sequence differences in these critical domains, measurements of receptor utilization, including host range and superinfection interference, confirmed the assignment of FeLV-945 to subgroup A. Other proviruses isolated from the cohort contained similar sequence hallmarks and were assigned to FeLV subgroup A. A provirus from cat 1046 contained a histidine-to-proline change at SU residue 6 within an SPHQ motif that was previously identified as a critical mediator of fusion events during virus entry. The 1046 pseudotype virus entered cells only in the presence of the soluble cofactor FeLIX provided in trans, but it retained an ecotropic host range even in the presence of FeLIX. The mutational changes in FeLV-945 were shown to confer significant functional differences compared to prototype FeLV-A viruses. The substitution of FeLV-945 envelope gene sequences for FeLV-A/61E sequences conferred a small but statistically significant replicative advantage in some feline cells. Moreover, substitution of the unique FeLV-945 long terminal repeat and envelope gene for those of FeLV-A/61E altered the disease spectrum entirely, from a thymic lymphoma of a T-cell origin to an as yet uncharacterized multicentric lymphoma that did not contain T cells.

]]> Chandtip Chandhasin et al. Androgenic Regulation of Growth Factor and Growth Factor Receptor Expression in the cwr22 Model of Prostatic Adenocarcinoma http://works.bepress.com/patricia_coan/6 http://works.bepress.com/patricia_coan/6 Fri, 05 Aug 2011 09:31:27 PDT The effects of androgen manipulation on epidermal growth factor (EGF) receptor, p185erbB-2 and transforming growth factor-α (TGF-α) levels were examined in prostatic adenocarcinoma. Male nude mice were inoculated with the CWR22 androgen-dependent human prostatic tumor or an androgen-independent (CWR22R) derivative. Mice with CWR22 tumors were castrated and subsequently killed at 3, 7, 21, 28 or 42 days post-castration. Other CWR22-bearing mice received s.c. testosterone pellets at 21 days post-castration and were killed 7 days later. EGF receptor, p185erbB-2 and TGF-α levels were examined by immuno-histochemistry. Strong EGF receptor and p185erbB-2 immunostaining was detected in CWR22 tumors from intact controls. EGF receptor immunostaining decreased by 65% to 70% at 21 to 42 days post-castration. Testosterone treatment at 21 to 28 days post-castration resulted in a 2-fold increase in EGF receptor immunostaining. p185erbB-2 immunostaining within CWR22 tumors did not decrease following castration and, in fact, was slightly increased at 7 days post-castration. The effects of castration on EGF receptor and p185erbB-2 levels were confirmed by Western blot analysis. Fewer than 10% of CWR22 tumor cells demonstrated strong TGF- immunostaining, and androgen manipulation did not effect TGF-α immunostaining. In contrast, 30% of androgen-independent CWR22R tumor cells were strongly immunostained for TGF-α. Our findings indicate that EGF receptor levels, but not p185erbB-2 levels, are strongly dependent on testosterone in CWR22 tumors. The co-localization of TGF-α and the EGF receptor in CWR22R tumors suggests that these factors may constitute an autocrine pathway that regulates androgen-independent growth.

]]> Russell B. Meyers et al. Changes in Cyclin Dependent Kinase Inhibitors p21 and p27 during the Castration Induced Regression of Prostatic Adenocarcinoma http://works.bepress.com/patricia_coan/5 http://works.bepress.com/patricia_coan/5 Fri, 05 Aug 2011 09:31:25 PDT Purpose

The expression of the cyclin dependent kinase inhibitors p21 and p27 was examined in prostatic adenocarcinomas following castration.

Materials and Methods

Male nude mice inoculated with the androgen dependent human prostatic tumor CWR22 were castrated when the tumors reached a volume of 0.8 to 1.1 cm.3 and were sacrificed at 3, 7, 21, 28 and 42 days post-castration. An additional group of mice received a subcutaneous testosterone pellet at 21 days post-castration and was sacrificed at 28 days post-castration. The expression of the Ki-67 antigen, p21 and p27 was examined by immunohistochemistry.

Results

The mitotic rate as well as the number of Ki-67 antigen positive cells decreased to 3% of intact control values by 7 days post-castration and were less than 0.01% of intact control values at 21, 28 and 42 days post-castration. The percentage of p21 expressing cells decreased from 15 +/− 2% in intact controls to less than 1% by 42 days post-castration. In contrast, the percentage of cells that expressed p27 increased from 25 +/− 3% in intact controls to 51 +/− 8% at 3 days post-castration and to 80 to 95% at days, 7, 21, 28 and 42 days post-castration. Testosterone treatment from 21 to 28 days post-castration resulted in an increase in Ki-67 antigen positive cells to 200% of intact controls and a concomitant reduction in p27 expressing cells to about 50% of intact controls. Castration-induced changes in p27 expression were not observed in the CWR22R tumor, a transplantable relapsed derivative of the CWR22 tumor.

]]> Russell B. Meyers et al. Effects of Viral Infections, Ammonia Exposure, Vitamin A Deficiency, and Age on Adherence of Mycoplasma Pulmonis to Rat Respiratory Epithelium http://works.bepress.com/patricia_coan/3 http://works.bepress.com/patricia_coan/3 Fri, 05 Aug 2011 09:31:23 PDT T. R. Schoeb et al. Pulmonary Clearance of Mycoplasma Pulmonis in Rats with Respiratory Viral Infections or of Susceptible Genotype http://works.bepress.com/patricia_coan/2 http://works.bepress.com/patricia_coan/2 Fri, 05 Aug 2011 09:31:21 PDT T. R. Schoeb et al.